Seizure activity induces profound changes in stem cell proliferation and neurogenesis, yet there is a fundamental gap in understanding the mechanism of seizure-induced neurogenesis and the relationship to epilepsy. The long-term goal is to better understand the epigenetic/transcriptional circuitry important for neuronal cell fate, in both physiological and pathological contexts. The objective of this grant proposal is to elucidate the role of the master regulator of neurogenesis NRSF, in adult hippocampal neural stem cells. The central hypothesis is that seizure activity triggers the dysregulation of NRSF and selects NRSF target genes that mediate aberrant neurogenesis and epileptogenesis. The rationale for the proposed research is that understanding the mechanisms of neurogenesis after pathologic stimuli, such as seizures, has the potential to understand the underlying repair response and neuroplasticity changes after brain injury, and evaluate the suitability of stem cells for neuro-regenerative medicine. Thus, the proposed study is relevant to that part of NIH's mission that relates to gaining fundamental knowledge that will potentially help treat neurological disorders, such as epilepsy. Guided by strong preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Identify the epigenetic/transcriptional mechanism that is responsible for NRSF regulation of neuronal cell fate;2) Determine how NRSF mediates aberrant neurogenesis after seizures using a single-cell genetic approach, and 3) Establish that NRSF contributes to seizure-induced neurogenesis and epileptogenesis using NRSF conditional knockout mice. Aims 1 and 2 will focus on the role of NRSF in neurogenesis, using gain-of-function and loss-of-function retroviral constructs to manipulate NRSF in vitro and during seizure-induced neurogenesis in vivo, which directly relate to the skills and experience in the Hsieh lab. Specific Aim 3 will be performed in collaboration with Dr. Christopher Sinton, and focus on the use of the NRSF conditional knockout mouse, to determine the role of NRSF in seizure-induced neurogenesis, and examine the contribution of aberrant neurogenesis to epileptogenesis. The approach is innovative, because it has the potential to explore the biology of adult neural stem cells and tap into their potential for cell replacement strategies after brain injury. The proposed work is significant, because it is expected to advance and expand our basic understanding of epigenetic/transcriptional regulatory mechanisms controlling neuronal cell fate after a wide range of pathologic stimuli, not just seizures. PUBLIC HEALTH RELEVANCE Disease, degeneration or traumatic injury of the nervous system are among the greatest public health concerns in the United States and are generally considered irreparable, often causing catastrophic damage to the functional capacity of the individual. Now, however, characterization of neural stem cells residing within specific germinal centers of the brain and in cell culture raises hope that functional regeneration of nervous tissue may be feasible, if we learn to exploit adult neurogenesis for clinical benefit. The research proposal will lead to improved understanding of neural stem cell biology, possibly leading to the development of new drugs for repair and regeneration of the nervous system.